In recent years, from the viewpoints of energy saving, resource saving, environmental load reduction and the like, there have been broadly utilized hot melt pressure-sensitive adhesives; and as base polymers for the hot melt pressure-sensitive adhesives, there are broadly used vinyl aromatic monomer-conjugated diene monomer-based block copolymers (for example, SBS; styrene-butadiene-styrene block copolymers and the like). Pressure-sensitive adhesive compositions obtained by using these block copolymers, however, are insufficient in the balance among holding power, tack and adhesive power, and these have been desired to be improved.
As improving methods, for example, Patent Literature 1 discloses a pressure-sensitive adhesive composition composed of a triblock copolymer and a diblock copolymer. Further, Patent Literature 2 discloses a pressure-sensitive adhesive composition composed of a block copolymer obtained by coupling with a specific bifunctional coupling agent (specific dihalogen compound). Furthermore, Patent Literature 3 discloses a pressure-sensitive adhesive composition composed of a block copolymer obtained by hydrogen-adding (hereinafter also simply referred to as “hydrogenating”), in a specific proportion, a block copolymer of a vinyl aromatic monomer and a conjugated diene monomer.